Portable wheelchairs capable of folding or collapsing have been in use for many years to accommodate wheelchair users who travel and need to take their wheelchairs with them and store them in space limited compartments. Typically, wheelchairs that are designed to fold or collapse incorporate a pair of diagonally extending cross members secured between a right and left frame member which may be scissored together to collapse the wheelchair. Although increasing the collapsibility and portability of the wheelchair, the typical cross member frame sacrifices strength and stability.
Additionally, standard cross member frame construction for portable wheelchairs is bulky and heavy, making transportation or storage difficult at best. Consequently, portable wheelchairs are not designed for storage in standard luggage compartments such as on airlines, trains and other mass transit mediums.
For example, U.S. Pat. No. 5,560,627 to Zatulovsky et al; U.S. Pat. No. 4,861,056 to Duffy, Jr. et al, and U.S. Pat. No. 5,154,438 to Barclay, incorporate various cross member support structures for maintaining stability of the frame. It is also well known in the art to incorporate a plurality of links that join an upper portion of the cross member to an adjacent upper portion of the frame and that pivot at least at the point where the link is connected to the cross tube member for controlled folding of the cross members and preventing the same from spreading apart when the wheelchair is in its fully expanded position.
Although the prior art addresses some of the structural criteria necessary for maintaining a portable wheelchair that is structurally stable, the present invention provides for a more compact, lightweight collapsible wheelchair that is both structurally stable and suitable for travel and storage in standard luggage compartments.